The pamphlet "Modern Money Mechanics," which explains M1, M2, and M3
in gory detail, was once available free from the Federal Reserve Bank
of Chicago. That pamphlet is no longer in print, and the Chicago Fed
apparently has no plans to re-issue it. However, electronic copies of
it are out there, and here's one:
http://landru.i-link-2.net/monques/mmm2.html